Energy auditors sometimes use a technology called thermography, or infrared scanning, in order to detect certain thermal defects and air leaks in the envelopes of buildings.
How Does Thermography Work?
Thermography works to measure key surface temperatures with the use of both infrared video and conventional still cameras. These helpful tools can accurately view light within the heat spectrum. Images on either the film or video record the variations of the temperature of the “skin” of the building, ranging from black (cooler) to white (warm) areas. The subsequent images help the energy auditor to determine whether or not insulation is needed for a particular area.
A professional thermographic assessment is either an exterior or interior survey. It’s up to the auditor to determine which method will offer the most revealing results given the weather conditions. The most common inspections are performed on the inside since warm air escaping from a building’s structure doesn’t always permeate the interior walls in a straight line. Detected heat loss from one section of an exterior wall may start off in another area on the interior of the wall. Also, it’s much more difficult to identify differences in temperature on a building’s exterior during a period of windy weather. Due to this challenge, surveys performed on the inside are typically more accurate since they aren’t working against any air movement.
Thermography utilizes unique infrared video or sometimes still cameras in order to create images called thermograms that reveal heat variations on various surfaces and also provide many other applications as well. Energy auditors often use thermography as a way to assist them in detecting air leaks and heat losses in buildings.
Infrared scanning lets auditors determine the effectiveness of a building’s insulation. The thermograms help energy auditors figure out if a building requires insulation and where exactly it needs to be implemented. Since wet insulation conduct heats much faster than drier insulation, thermographic roof scans can accurately detect the leaks in a roof.
Because even newly constructed homes can have imperfections in their thermal envelopes, it’s also best to have a scan performed prior to purchasing a new home.
Various Types of Thermography Devices
A professional energy auditor may employ one of many different types of infrared tools during an inspection. Here are some of the most commonly used devices:
A spot radiometer is a simple device that auditors use to measure levels of radiation one area at a time with the use of a meter reading that reveals the temperature of any given spot. The energy auditor uses the device to pan the area and takes note of any temperature variations; however this is very time consuming and very easy to miss issues.
Thermal Imaging Camera
A thermal imaging camera is the most accurate device used in detecting heat leakage areas. Both thermal line scanners and spot radiometers don’t provide enough detail for an entire home energy evaluation in the same way a thermal imaging camera can.
How to Prepare for a Thermographic Inspection
The homeowner needs to take certain steps to ensure accurate results for a home interior thermal scan. This could likely involve pulling furniture away from walls and temporarily removing window treatments. The most precise thermographic images typically happen when there’s a significant temperature difference between outside and inside temperatures. In the southern states, thermographic scans are generally conducted during the warmer months when the air conditioner is on, while in the northern states, scans are usually performed in the colder months.
At various times during the year it may be necessary for some homeowners to produce and maintain a detailed outside and inside temperature difference for as long as four hours prior to the test. Turning on the central heat in warm climates or running the AC in cooler climates can do this. Ask your energy auditor prior to the scheduled test if it’s necessary for you to do these particular tasks.